Devices are known for counting products using a matrix camera requiring the set-up of a calibration procedure thus resulting in a complex and costly apparatus.
French patent FR 2 680 027 discloses an apparatus for counting memory cards contained in opaque packaging. The apparatus comprises an electronic module and means for driving of the packaging for moving it between a source of x-rays and a detector connected to a processing circuit. The packaging as well as the card bodies being transparent to the x-rays, the detector receives a beam modified by the shadow of the electronic modules of the cards. The processing circuit can count the pulses corresponding to the passage of each module or enable display of the images obtained during the complete travel of the package between the detector and the x-ray emitter. This device can be used only for counting product having a metallic element or more generally a part that is opaque to x-rays. In addition, the x-ray source must be precisely set up so as to emit a reduced energy beam in order not to alter the opaque part.
European patent EP 676 718 discloses a device for counting thin products stacked side-by-side in a tray packaged in a translucent shrinkable film. This device comprises means for illuminating the tray, mirrors enabling transmission of the light beam reflected by the edge of the products to a linear camera, comprised of photosensitive elements, and means for transverse displacement of the tray in such a way as to carry out multiple scans, each scan being made transverse to the movement of the tray. Counting of the products is done by alternating detection of peaks and valleys. A drawback of this device is that the illumination means, the mirrors and the camera occupy considerable space. Another drawback of this device is that the measurement time is considerable due to the fact that each scan is done over the entire length of the tray.